Pin connector structure and method

ABSTRACT

Embodiments pin connections, electronic devices, and methods are shown that include pin configurations to reduce voids and pin tilting and other concerns during pin attach operations, such as attachment to a chip package pin grid array. Pin head are shown that include features such as convex surfaces, a number of legs, and channels in pin head surfaces.

PRIORITY APPLICATION

This application is a divisional of U.S. application Ser. No.13/533,681, filed Jun. 26, 2012, which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

Embodiments pertain to integrated circuit (IC) dies and die packages,and associated methods.

BACKGROUND

Semiconductor dies are often coupled to other circuitry in an electronicsystem through a substrate. The substrate includes interconnectioncircuitry that routes power and data between other electrical componentsand the semiconductor die that is coupled to the substrate.

In pin connection structures, such as pin grid arrays, improvedmechanical integrity and conductivity are desired. Voids in a joiningmatrix material can be detrimental in a number of ways, includingreducing mechanical integrity and/or causing tilting of pins. It isdesired to improve pin stability and to reduce voids in a matrixmaterial joining pins to a substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross section view of an IC package in accordance with someembodiments;

FIG. 2 is cross section view of a pin connection in accordance with someembodiments;

FIG. 3 is cross section view of another pin connection in accordancewith some embodiments;

FIG. 4 is an isometric view of a pin in accordance with someembodiments;

FIG. 5 is an isometric view of a pin in accordance with someembodiments;

FIG. 6 is an isometric view of a pin in accordance with someembodiments;

FIG. 7 is an isometric view of a pin in accordance with someembodiments;

FIG. 8 is a flow diagram of a method in accordance with someembodiments; and

FIG. 9 is a block diagram of an electronic system in accordance withsome embodiments.

DETAILED DESCRIPTION

The following description and the drawings sufficiently illustratespecific embodiments to enable those skilled in the art to practicethem. Other embodiments may incorporate structural, logical, electrical,process, and other changes. Portions and features of some embodimentsmay be included in, or substituted for, those of other embodiments.Embodiments set forth in the claims encompass all available equivalentsof those claims.

FIG. 1 shows a cross-sectional representation of an IC package 100. Inembodiments where the IC die is a processor die, the IC package can betermed a processor assembly. IC package 100 includes an IC die 110mounted in “flip-chip” orientation with its active side facing downwardto couple with an upper surface of a substrate 120, throughinterconnections 112 such as solder balls or bumps. The substrate 120also shows pins 122 on its opposite surface to form a pin grid array(PGA) for mating with additional packaging structure (not shown).

Die 110 generates its heat from internal structure, including wiringtraces, located near its active side; however, a significant portion ofthe heat is dissipated through its back side 114. Heat that isconcentrated within the die is dissipated to a large surface that is incontact with the die in the form of an integrated heat spreader 130. Athermal interface material 140 is often provided between the die 110 andintegrated heat spreader 130. In one embodiment, to further dissipateheat from the integrated heat spreader 130, a heat sink 150 optionallyhaving fins 152 is coupled to the integrated heat spreader 130.

FIG. 2 shows one example of a pin connection 200. The pin connection 200includes a portion of a substrate 230 similar to substrate 120 fromFIG. 1. An electrical connection 232 is shown on the substrate 230. Apin 210, including a pin point 212 and a pin head 214, is shown coupledto the electrical connection 232 by embedding the pin head 214 in amatrix material 220. In one example, the matrix material 220 includessolder. Other examples of matrix materials may include metals orpolymers. In one example, the matrix material includes a tin-antimonysolder, although other solder compositions are also within the scope ofembodiments of the invention.

During fabrication of a pin connection, gas bubbles may be generated atduring application of the matrix material 220. Gas bubbles can causedetrimental effects, such as voids in the resulting matrix material,and/or tilting of the pin 210. It is desired to provide a pin connection200 with good alignment, and few or no voids to increase conductivity,and to provide good mechanical integrity to hold the pin in place duringattachment or removal from a corresponding socket.

The pin 210 shown in FIG. 2, includes a pin head 214 having a bottomsurface 218, and a substantially convex top surface 216. A portion ofthe substantially convex top surface 216 forms an interface 217 with theelectrical connection 232 such that the pin head 214 will stand upduring application of the matrix material 220.

In one example, the substantially convex top surface 216 channels anygas bubbles away from between the electrical connection 232 and the pinhead 214. In examples where the pin head is down, and the pin point isup during application of the matrix material 220, the gas bubbles willfloat upwards along the convex top surface 216, and not become trappedat the interface between the electrical connection 232 and the pin head214. Trapped gas bubbles may cause pin tilting or voids within thematrix material.

FIG. 3 shows another example of a pin connection 300. The pin connection300 includes a portion of a substrate 330 similar to substrate 120 fromFIG. 1, and substrate 230 from FIG. 2. An electrical connection 332 isshown on the substrate 330. A pin 310, including a pin point 312 and apin head 314, is shown coupled to the electrical connection 332 byembedding the pin head 314 in a matrix material 220 such as solder.

The pin 310 shown in FIG. 3, includes a pin head 314 having a bottomsurface 318, and number of legs 316 extending at least partially awayfrom the pin head 314 in a direction away from the point 312 of the pin310. In one example, the pin head 314 includes three or more legs 316that stabilize the pin 310 such that the pin head 314 will stand upduring application of the matrix material 320. In examples using onlythree legs, the three legs form a stable plane, with no potential forone leg being slightly too short or too long. Although three legs areshown in FIG. 3, other numbers of legs 316 are also within the scope ofthe invention.

In one example, the legs 316 provide a space between the legs 316, andbeneath the pin head 314 that channels any gas bubbles away from betweenthe electrical connection 332 and the pin head 314.

FIG. 4 shows an example of a pin 410 for use in a pin connection such asa pin grid array. The pin 410 includes a pin head 414 having a bottomsurface 418, and number of legs 416 extending at least partially awayfrom the pin head 414 in a direction away from a point 412 of the pin410. In the example of FIG. 4, the legs 416 extend in a direction thatis substantially directly opposite the point 412 of the pin 410. Otherexamples may include legs 416 that extend at an angle away from the pin410, with a component of the leg direction extending away from the pinhead in a direction away from a point of the pin. In such aconfiguration, the leg 416 is extending only partially away from the pinhead in a direction away from a point of the pin.

A space 422 is provided between the legs 416 and beneath the pin head414 that will channel any gas bubbles away during an attachmentoperation using a matrix material such as solder.

The pin head 414 of FIG. 4 further includes at least a portion of a flatbottom surface 418. Flat portions such as bottom surface 418 may provideincreased mechanical stability, making the pin more resistant to pullingout of the matrix material when inserting or removing the pin 410 from acorresponding socket.

FIG. 5 shows an example of a pin 510 for use in a pin connection such asa pin grid array. The pin 510 includes a pin head 514 having a bottomsurface 518, and a number of legs 516 extending at least partially awayfrom the pin head 514 in a direction away from a point 512 of the pin510. A space 522 is provided between the legs 516 and beneath the pinhead 514 that will channel any gas bubbles away during an attachmentoperation using a matrix material such as solder.

FIG. 6 shows an example of a pin 610 for use in a pin connection such asa pin grid array. The pin 610 includes a pin head 614 having a bottomsurface 618, and a substantially convex top surface 616. The example ofFIG. 6 further includes a number of legs 620 extending at leastpartially away from the pin head 614 in a direction away from a point612 of the pin 510.

The example of FIG. 6 includes three legs 620 that stabilize the pin 610such that the pin head 614 will stand up during application of matrixmaterial. The substantially convex top surface 616 channels any gasbubbles away from between an electrical connection and the pin head 614.In addition to the convex surface, the example of FIG. 6 also provides aspace between the legs 616 to channel any gas bubbles away during anattachment operation using a matrix material such as solder.

FIG. 7 shows an example of a pin 710 for use in a pin connection such asa pin grid array. The pin 710 includes a pin head 714 having a bottomsurface 718, and a substantially convex top surface 716. The example ofFIG. 7 includes a cavity 720 that defines a rim 722. In one example, therim 722 provides stability to keep the pin head 714 standing during anattachment operation using a matrix material such as solder.

The pin head 714 of FIG. 7 also illustrates a pattern 724 formed on thesubstantially convex top surface 716. In one example, the pattern 724includes one or more channels that aid in removal of any gas bubblesaway during an attachment operation using a matrix material such assolder.

FIG. 8 shows one example of a method of forming a pin connection. Inoperation 802, a pin is formed, including a pin head having at leastthree legs extending at least partially away from the pin head in adirection away from a point of the pin. In operation 804, the pin headis placed in contact with an electrical connection on a substratesurface. In operation 806, solder is flowed around the pin head and incontact with the electrical connection to embed the pin head. Inoperation 808, gas bubbles are channeled from beneath the pin head usinggaps formed by the at least three legs.

In some example methods, a substantially convex top surface is alsoformed on the pin head. In some example methods, one or more grooves arefurther formed in the substantially convex top surface. Structures suchas channels may be formed by casting, forging, etching, etc. into thesubstantially convex top surface 716.

An example of an electronic device using semiconductor chips and pinconnection structures as described in the present disclosure is includedto show an example of a higher level device application for the presentinvention. FIG. 9 is a block diagram of an electronic device 900incorporating at least one pin and/or method in accordance with at leastone embodiment of the invention. Electronic device 900 is merely oneexample of an electronic system in which embodiments of the presentinvention can be used. Examples of electronic devices 900 include, butare not limited to personal computers, tablet computers, mobiletelephones, game devices, MP3 or other digital music players, etc. Inthis example, electronic device 900 comprises a data processing systemthat includes a system bus 902 to couple the various components of thesystem. System bus 902 provides communications links among the variouscomponents of the electronic device 900 and can be implemented as asingle bus, as a combination of busses, or in any other suitable manner.

An electronic assembly 910 is coupled to system bus 902. The electronicassembly 910 can include any circuit or combination of circuits. In oneembodiment, the electronic assembly 910 includes a processor 912 whichcan be of any type. As used herein, “processor” means any type ofcomputational circuit, such as but not limited to a microprocessor, amicrocontroller, a complex instruction set computing (CISC)microprocessor, a reduced instruction set computing (RISC)microprocessor, a very long instruction word (VLIW) microprocessor, agraphics processor, a digital signal processor (DSP), multiple coreprocessor, or any other type of processor or processing circuit.

Other types of circuits that can be included in electronic assembly 910are a custom circuit, an application-specific integrated circuit (ASIC),or the like, such as, for example, one or more circuits (such as acommunications circuit 914) for use in wireless devices like mobiletelephones, pagers, personal data assistants, portable computers,two-way radios, and similar electronic systems. The IC can perform anyother type of function.

The electronic device 900 can also include an external memory 920, whichin turn can include one or more memory elements suitable to theparticular application, such as a main memory 922 in the form of randomaccess memory (RAM), one or more hard drives 924, and/or one or moredrives that handle removable media 926 such as compact disks (CD),digital video disk (DVD), and the like.

The electronic device 900 can also include a display device 916, one ormore speakers 918, and a keyboard and/or controller 930, which caninclude a mouse, trackball, touch screen, voice-recognition device, orany other device that permits a system user to input information intoand receive information from the electronic device 900.

VARIOUS NOTES & EXAMPLES

Example 1 can include subject matter (such as an apparatus, a method, ameans for performing acts) that can include or use a pin grid array. Thepin grid array can include a substrate, including a number of electricalconnections. The pin grid array can include a matrix material forming aninterface with the electrical connections on the substrate. The pin gridarray can include a number of pins having pin heads embedded in thematrix, wherein one or more pins includes a pin head having asubstantially convex top surface.

Example 2 can include, or can optionally be combined with the subjectmatter of Example 1 to include wherein the matrix material includessolder.

Example 3 can include, or can optionally be combined with the subjectmatter of Examples 2 to include wherein the solder includes atin-antimony solder.

Example 4 can include, or can optionally be combined with the subjectmatter of any one or more of Examples 1 through 3 to include at leastthree legs extending at least partially away from the pin head in adirection away from a point of the pin.

Example 5 can include, or can optionally be combined with the subjectmatter of any one or more of Examples 1 through 4 to include wherein thesubstantially convex top surface includes a textured surface.

Example 6 can include, or can optionally be combined with the subjectmatter of any one or more of Examples 1 through 5 to include wherein thetextured surface includes one or more channels.

Example 7 can include a pin grid array. The pin grid array can include asubstrate, including a number of electrical connections, a matrixmaterial forming an interface with the electrical connections on thesubstrate, and a number of pins having pin heads embedded in the matrix,wherein one or more pins includes a pin head having at least three legsextending at least partially away from the pin head in a direction awayfrom a point of the pin.

Example 8 can include, or can optionally be combined with the subjectmatter of Example 7 to include wherein the at least three legs extend ina direction directly opposite the point of the pin.

Example 9 can include, or can optionally be combined with the subjectmatter of any one or more of Examples 7 through 8 to include wherein thematrix material includes solder.

Example 10 can include, or can optionally be combined with the subjectmatter of any one or more of Examples 7 through 9 to include wherein thesolder includes a tin-antimony solder.

Example 11 can include an electronic device. The electronic device caninclude a substrate, including a number of top side and bottom sideelectrical connections, a semiconductor chip attached to the substrateusing the top side electrical connections, a matrix material forming aninterface with the bottom side electrical connections on the substrate,and a number of pins having pin heads embedded in the matrix, whereinone or more pins includes a pin head having a substantially convex topsurface.

Example 12 can include, or can optionally be combined with the subjectmatter of Example 11 to include wherein the semiconductor chip includesa processor.

Example 13 can include, or can optionally be combined with the subjectmatter of any one or more of Examples 11 through 12 to include a memorydevice coupled to the semiconductor chip.

Example 14 can include, or can optionally be combined with the subjectmatter of any one or more of Examples 11 through 13 to include at leastthree legs extending at least partially away from the pin head in adirection away from a point of the pin.

Example 15 can include a method of forming a pin connection. The methodcan include forming a pin, including a pin head having at least threelegs extending at least partially away from the pin head in a directionaway from a point of the pin, placing the pin head in contact with anelectrical connection on a substrate surface, and flowing solder aroundthe pin head and in contact with the electrical connection to embed thepin head.

Example 16 can include, or can optionally be combined with the subjectmatter of Example 15 to include channeling gas bubbles from beneath thepin head using gaps formed by the at least three legs.

Example 17 can include, or can optionally be combined with the subjectmatter of any one or more of Examples 15 through 16 to include forming asubstantially convex top surface on the pin head.

Example 18 can include, or can optionally be combined with the subjectmatter of any one or more of Examples 15 through 17 to include formingone or more channels in the substantially convex top surface.

Example 19 can include, or can optionally be combined with the subjectmatter of any one or more of Examples 15 through 18 to include whereinthe pin grid connection is formed as part of a pin grid array.

Each of these non-limiting examples can stand on its own, or can becombined with one or more of the other examples in any permutation orcombination.

The above detailed description includes references to the accompanyingdrawings, which form a part of the detailed description. The drawingsshow, by way of illustration, specific embodiments in which theinvention can be practiced. These embodiments are also referred toherein as “examples.” Such examples can include elements in addition tothose shown or described. However, the present inventors alsocontemplate examples in which only those elements shown or described areprovided. Moreover, the present inventors also contemplate examplesusing any combination or permutation of those elements shown ordescribed (or one or more aspects thereof), either with respect to aparticular example (or one or more aspects thereof), or with respect toother examples (or one or more aspects thereof) shown or describedherein.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In this document, the terms “including” and “inwhich” are used as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, device,article, composition, formulation, or process that includes elements inaddition to those listed after such a term in a claim are still deemedto fall within the scope of that claim. Moreover, in the followingclaims, the terms “first,” “second,” and “third,” etc. are used merelyas labels, and are not intended to impose numerical requirements ontheir objects.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) may be used in combination with each other. Otherembodiments can be used, such as by one of ordinary skill in the artupon reviewing the above description. The Abstract is provided to complywith 37 C.F.R. §1.72(b), to allow the reader to quickly ascertain thenature of the technical disclosure. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims. Also, in the above Detailed Description,various features may be grouped together to streamline the disclosure.This should not be interpreted as intending that an unclaimed disclosedfeature is essential to any claim. Rather, inventive subject matter maylie in less than all features of a particular disclosed embodiment.Thus, the following claims are hereby incorporated into the DetailedDescription, with each claim standing on its own as a separateembodiment, and it is contemplated that such embodiments can be combinedwith each other in various combinations or permutations. The scope ofthe invention should be determined with reference to the appendedclaims, along with the full scope of equivalents to which such claimsare entitled.

What is claimed is:
 1. A pin grid array, comprising; a substrate, including a number of electrical connections; a matrix material forming an interface with the electrical connections on the substrate; and a number of pins including pin shafts, and having pin heads embedded in the matrix, wherein one or more pins includes a pin head having at least three legs extending at an angle with respect to the pin shaft between, but not including 0 and 90 degrees.
 2. The pin grid array of claim 1, wherein the pin head includes a textured top surface.
 3. The pin grid array of claim 2, wherein the textured top surface includes one or more channels.
 4. The pin grid array of claim 1, wherein the matrix material includes solder.
 5. The pin grid array of claim 4, wherein the solder includes a tin-antimony solder.
 6. A method of forming a pin connection, comprising: forming a pin, including a pin head having at least three legs extending at an angle with respect to the pin shaft between, but not including 0 and 90 degrees; placing the pin head in contact with an electrical connection on a substrate surface; and flowing solder around the pin head and in contact with the electrical connection to embed the pin head.
 7. The method of claim 6, further including channeling gas bubbles from beneath the pin head using gaps formed by the at least three legs.
 8. The method of claim 6, further including forming one or more channels in the top surface.
 9. The method of claim 6, wherein the pin grid connection is formed as part of a pin grid array. 